Improvement in mainsprings for watches



G, HUNTER.-

Main-Springs for Watches.

N0 161,236l Patented March 23,1875.

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UNITED STATES PATENT FFICE.

GEORGE HUNTER, OF ELGIN, ILLINOIS,

IMPROVEMENT IN MAlNSPRlNGS FOR WATCHES.

Specification forming part of Letters Patent No. 161,236, dated March 23, 1875; application filed October l, 1873.

To all ywhom 'it may concern:

Be it known that I, Gnonen HUNTER, of Elgin in the county of Kane and State of Illinois, have invented certain new and useful Improvements in llainsprings for Vatohes; and do hereby declare that the following is a l'ull, clear, and exact description thereof, reference being had 'to the accompanying drawings, making a part of this speeilication, in which- Figure l is a perspective view of the outer end ot' a mainspring prepared for engagement with a winding-barrel. Fig. 2 is a plan view of said spring' in position. within a barrel and unwound; and Fig. is a like view of the same when wound up.

Letters of like name and kind refer to like parts in each otl the iiguies.

The design ot' my invention is to increase the ease and certainty ol" the engagement of the outer end ot' a mainspring with the winding-barrel ot a watch, and to enable the full size ot' the interior ot' said barrel to be utilized, so as thereby to permit an increase in the usual length ofthe spring; and it consists in providing, near the outer end oi" a mainspring, a tongue that extends forward, and slightly outward, so as to engage with a suitable notch in the interior of the barrel, which tongue is cut from said spring, and may be pressed into the opening formed therein, so as not to increase the space occupied by the same within said barrel, substantially as and for the purpose hereinafter specified.

In the annexed drawing, A represents an ordinary mainspring for a watch, constructed in the usual manner, except at or near its outer end, at which point is formed a tongue, a, that extends iorward and slightly outward, as shown in Fig. l. rllhe tongue a is constructed from the spring A, by cutting along its sides and across its forward end, its rear end being a part of said spring', after which a slight outward curve is given, and said tongue suitably tempered. The spring A is placed within an ordinary barrel, B, and has its inner end connected in the usual manner to or with a winding-arbor, O, while at its outer end the forward end of the tongue c enga-ges with a corresponding notch, b, that is formed within the inner side of said barrela Upon winding the spring, the strain has a tendency to cause the tongue to engage more closely with its notch, while the outer end of said spring, not being rigidly attached to said barrel, is at liberty to assume any position within the space between the inner side ot' the latter and the contiguous coil of said spring, so as thereby to cause the strain upon said part to be in a direct line, and thus avoid the usual liability to breakage which exists when such strain is oblique.

Vhen the spring' A is unwound, its tongue d will be contained within the opening a. from which it was out, and permit the end of said spring to bear directly against the inner side ofthe barrel B, by which means, as said engaging device occupies no radial space within said barrel, a spring can be employed which contains one or more coils in addition to those which could be contained by said barrel were any ordinary method ot' attachment used, the result of such increase in the length ot' the mainspring being' an increase in the regularity with which the watch movement will be driven.

I am aware that mainsprings have before been connected to or with winding barrels by bending or doubling their outer ends i'orward, so as to forni a hook, and causing the same to engage with a notch, stud, or opening formed in or attached to the inner side ot' a barrel, and therefore do not claim such construction.

Having thus fully set forth the nature and merits of myinvention, what I claim as new 1s The mainspring A, provided at or near its outer end with the tongue a, which tongue is cut from the opening c', and extends forward and slightly outward, in combination with the windingbarrel B, provided within its inner side with the engaging notch b, substantially as and for the purpose specified.

In testimony that I claim the foregoing I have hereunto set my hand this 24th day of September, 1874.

GEORGE HUNTER.

Witnesses:

JNO. H. WHIPPLE, J AcKsoN W. ALWARD. 

